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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules and EC225LP helicopters. The FAA
issued AD 20161251 to address an accident involving an EC225LP
helicopter in which the main rotor hub detached from the MGB. The Airbus Helicopters Model AS332L2 helicopter has a similar design to the affected Model EC225LP helicopter, therefore, this model may be subject to the unsafe condition revealed on the Model EC225LP helicopter.

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Actions Since AD 20161251 Was Issued Since the FAA issued AD 201612
51, the design approval holder has developed procedures that address failure of the main rotor system. These procedures terminate the flight prohibition required by AD 20161251.
In addition, after AD 20161251 was issued, the FAA issued an Alternate Means of Compliance AMOC letter dated September 7, 2017, which addressed the flight prohibition required by paragraph e of AD 2016
1251. The AMOC letter lifted the flight prohibition and allowed operation of the affected helicopter models provided the conditions specified in the AMOC
letter were followed, which include repetitive inspections that have no terminating action. This proposed AD
includes terminating action for certain repetitive inspections.
The EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD
20170134R2, dated April 16, 2020
EASA AD 20170134R2 also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI, to correct an unsafe condition for all Airbus Helicopters Model AS332L2 and EC225LP helicopters.
This proposed AD was prompted by an accident involving a Model EC225LP
helicopter in which the main rotor hub detached from the MGB. The FAA is proposing this AD to address failure of the main rotor system, which would result in loss of control of the helicopter. See the MCAI for additional background information.
Related Service Information Under 1
CFR Part 51
EASA AD 20170134R2 references procedures for replacing certain second stage planet gear assemblies with serviceable parts; removing certain epicyclic modules from service;
modifying the helicopter by installing an FFMP; revising the RFM to prohibit MGB particle burning in-flight;
repetitively inspecting the FFMP and MGB particle detectors for metal particles, analyzing any metal particles that are found, and corrective action;

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and repetitively inspecting the MGB oil filter and oil cooler for particles and corrective action. The corrective actions include replacing an affected MGB with a serviceable MGB. EASA AD 2017
0134R2 also provides terminating action for certain repetitive inspections.
Airbus Helicopters has issued Emergency Alert Service Bulletin EC225
05A049, Revision 6, dated July 25, 2017;
and Emergency Alert Service Bulletin AS 332 05.01.07, Revision 6, dated July 27, 2017. The service information specifies procedures for, among other things, replacing the MGB.
This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

regulatory text of this proposed AD.
Using common terms that are the same as the heading of a particular section in the EASA AD does not mean that operators need comply only with that section. For example, where the AD
requirement refers to all required actions and compliance times, compliance with this AD requirement is not limited to the section titled Required Actions and Compliance Times in the EASA AD. Service information specified in EASA AD
20170134R2 that is required for compliance with EASA AD 2017
0134R2 will be available on the internet at https www.regulations.gov by searching for and locating Docket No.
FAA20210379 after the FAA final rule is published.

FAAs Determination and Requirements of This Proposed AD
These products have been approved by the aviation authority of another country, and are approved for operation in the United States. Pursuant to the bilateral agreement with the State of Design Authority, the FAA has been notified of the unsafe condition described in the MCAI referenced above. The FAA is proposing this AD
after evaluating all the relevant information and determining the unsafe condition described previously is likely to exist or develop in other products of these same type designs.

Differences Between This Proposed AD
and the MCAI
Although the service information referenced in EASA AD 20170134R2
specifies to return affected planetary gear assemblies to the manufacturer for module overhaul, this proposed AD
does not include that requirement.
Although the service information referenced in EASA AD 20170134R2
specifies that retrofit of the planet gear of the MGB can only be done by Airbus Helicopters or Airbus Helicopters approved repair centers, this proposed AD does not include that requirement.
EASA AD 20170134R2 requires operators to inform all flight crews of revisions to the RFM, and thereafter to operate the helicopter accordingly.
However, this AD would not specifically require those actions.
FAA regulations require pilots to follow the procedures in the existing RFM including all updates. 14 CFR 91.9
requires that no person may operate a civil aircraft without complying with the operating limitations specified in the RFM. Therefore, including a requirement in this AD to operate the airplane according to the revised RFM
would be redundant and unnecessary.
Further, compliance with such a requirement in an AD would be impracticable to demonstrate or track on an ongoing basis; therefore, a requirement to operate the airplane in such a manner would be unenforceable.

Proposed AD Requirements This proposed AD would require accomplishing the actions specified in EASA AD 20170134R2 described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this AD and except as discussed under Differences Between this Proposed AD and the MCAI.
Explanation of Required Compliance Information In the FAAs ongoing efforts to improve the efficiency of the AD
process, the FAA initially worked with Airbus and EASA to develop a process to use certain EASA ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has since coordinated with other manufacturers and civil aviation authorities CAAs to use this process. As a result, EASA AD
20170134R2 will be incorporated by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2017
0134R2 in its entirety, through that incorporation, except for any differences identified as exceptions in the
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Interim Action The FAA considers this proposed AD
interim action. If final action is later identified, the FAA might consider further rulemaking then.
Costs of Compliance The FAA estimates that this proposed AD affects 28 helicopters of U.S.
registry. The FAA estimates the
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